1. Field of the Disclosure
This disclosure relates to a flexible display device, and more particularly to a flexible display device and a manufacturing method thereof.
2. Description of the Related Art
It is a recent trend that flexible substrates that are thin and light and exhibit superior anti-shock characteristics are widely used in the manufacture of electronic devices. Display devices using flexible substrates are liquid crystal display devices, organic electro-luminescence display devices, and electro-phoresis display devices. The flexible display devices may be applied to smart cards, wearable computers, and electronic paper.
A flexible display device includes a display panel and driving portion. The display panel includes a display zone for displaying an image through a plurality of pixels arranged in the shape of a matrix; and a non-display zone where an image is not displayed, connected to the driving portion. The driving portion includes a gate TCP (tape carrier package) where a gate driver is mounted and a data TCP where a data driver is mounted. A gate pad portion connected to the gate TCP and a data pad portion connected to the data TCP are arranged in the non-display zone. For example, an electro-phoresis display device includes a thin film transistor (TFT) substrate on which a plurality of TFTs for driving the pixels are arranged. An ink substrate having an ink layer is attached on the TFT substrate, thus forming a display panel. The TFT substrate is formed by press cutting a mother substrate.
FIG. 1 is a plan view of a flexible display device of related art. Referring to FIG. 1, a plurality of TFT substrates 3 corresponding to the size of a display panel are provided on a mother substrate 1.
FIG. 2 illustrates the structure of one of the TFT substrates 3 of FIG. 1. referring to FIG. 2, each of the TFT substrates 3 of FIG. 1 includes a display zone D in which a plurality of pixels are arranged and a non-display zone ND in which a plurality of gate pad portions 12 and a plurality of data pad portions 16 are arranged. In the display zone D, a plurality of gate lines 10 and a plurality of data lines 14 are arranged crossing each other. A plurality of pixels P are defined as the gate lines 10 and the data lines 14 cross each other. A TFT 18 is connected to each of the gate lines 10 and each of the data lines 14 arranged in each pixel P. The gate pad portions 12 in the non-display zone ND are connected to the gate lines 10 in the display zone D. The data pad portions 16 in the non-display zone ND are connected to the data lines 14 in the display zone D.
FIG. 3 is a cross-sectional view showing a TFT region of each pixel and the gate pad region 12 and the data pad region 16 in the non-display zone ND. Referring to FIG. 3, a barrier film 23 formed of an insulation material is formed on the mother substrate 1 that is flexible and formed of metal. The barrier film 23 is formed to prevent electric short-circuits between the mother substrate 1 and the gate lines 10, a gate electrode 25, and a gate pad electrode 27, which will be formed later.
The gate lines 10, the gate electrode 25, and the gate pad electrode 27 are formed on the barrier film 23, and a gate insulation film 29 is formed on the barrier film 23 in which the gate lines 10, the gate electrode 25, and the gate pad electrode 27 are provided. A semiconductor layer 31 is formed on the gate insulation film 29 corresponding to the gate electrode 25.
The data lines 14, source and drain electrodes 33 and 35, and a data pad electrode 37 are formed on the mother substrate 1 including the semiconductor layer 31. Next, a protective film 39 is formed on the mother substrate 1 with the semiconductor layer 31. Then, a pixel electrode 41, a gate contact electrode 43, and a data contact electrode 45 are formed on the protection film 39. The pixel electrode 41 is connected to the drain electrode 35, the gate contact electrode 43 is connected to the gate pad electrode 27, and the data contact electrode 45 is connected to the data pad electrode 37.
Accordingly, the barrier film 23, the gate pad electrode 27, the gate insulation film 29, the protection film 39, and the gate contact electrode 43 are formed in a gate pad region. Also, the barrier film 23, the gate insulation film 29, the data pad electrode 37, the protection film 39, and the data contact electrode 45 are formed in a data pad region.
After the TFT 18, the gate pad portions 12, and the data pad portions 16 are formed, the mother substrate 1 undergoes a cutting process. Since the mother substrate 1 is formed of metal, the mother substrate 1 is cut using a press machine. That is, as shown in FIG. 4, when the mother substrate 1 is accommodated on a support 51, the mother substrate 1 is pressed by a presser 53 to be physically cut so that a TFT substrate is manufactured. Thus, the gate pad region or the data pad region is positioned at a portion to be cut.
Accordingly, when the mother substrate is cut by being physically pressed in the press machine, an edge portion of the TFT substrate is burred or crashed, which may lift each layer of the substrate or generate cracks or disconnection lines in the substrate. Furthermore, during the pressing process, the layers of the substrate in the vicinity of a cut line may be separated and attached to the TFT substrate so that line short-circuits can be generated.